This invention relates generally to improvements in devices and systems for cooling a supply of water used for drinking, cooking, etc. More particularly, this invention relates to improvements in a water cooler of the type equipped with a compact thermoelectric heat transfer module for quietly chilling water within a cooler reservoir.
Bottled water coolers are well known in the art for containing a supply of relatively purified water in a convenient manner and location ready for substantially immediate dispensing and use. Such water coolers commonly include an upwardly open reservoir adapted to receive and support a water bottle of typically three to five gallon capacity in an inverted orientation such that bottled water may flow downwardly into the cooler reservoir. A spigot on the front of a cooler housing is operable at any time to dispense the water in selected amounts. Such bottled water coolers are widely used to provide a clean and safe source of drinking water, especially in areas wherein the local water supply may or is suspected to contain undesired levels of contaminants. Alternative so-called point-of-use water coolers are also known in the art wherein the cooler is connected to a water supply line and includes water filtration and/or purification means such as a reverse osmosis unit for purifying water supplied to the cooler reservoir.
In many water coolers of the type described above, it is desirable to refrigerate the water within the cooler reservoir to a relatively low temperature to provide a highly pleasing and refreshing source of drinking water. However, refrigeration equipment for such water coolers has typically comprised conventional compressor-type mechanical refrigeration systems which undesirably increase the overall cost, complexity, size, operational noise level, and power consumption requirements of the water cooler. Alternative cooling system proposals have suggested the use of relatively compact and quiet thermoelectric heat transfer modules, such as the system shown and described in U.S. Pat. No. 5,072,590. In such proposals, a thermoelectric module is mounted with a cold side thereof disposed in heat transfer relation with water in the cooler reservoir, and a hot side associated with a heat sink for dissipating heat drawn from the water. A cooling fan is normally provided to circulate air over the heat sink for improved heat transfer efficiency.
While thermoelectric chiller systems are relatively simple in construction and quiet in operation, such systems have nevertheless exhibited important drawbacks which have limited their widespread adoption and use. More specifically, the chilling capacity of the thermoelectric module is relatively small as compared to a conventional compressor-type refrigeration system, resulting in a relatively slow recovery time following a large withdrawal or several successive withdrawals of water from the reservoir. To offset this problem, the thermoelectric module has typically been operated so as to develop an ice bank within the reservoir for substantially immediate chilling of make-up water following a large withdrawal. Unfortunately, this reliance upon an ice bank for prompt chilling of make-up water requires the thermoelectric module to be operated substantially on a full-time basis, with resultant excessive energy use and risk of freeze-up of the reservoir. One attempt to control ice bank growth has involved the use of baffles disposed within the reservoir in a position intended to prevent reservoir freeze-up, but the use of such baffles does not address the problem of excessive energy usage. Another attempt has involved regulation of the heat transfer rate from the reservoir by speed control of the cooling fan used to circulate a convective air flow over the heat sink, in response to variations in ambient air temperature. However, this latter approach also does not address the problem of excessive energy usage, and further has been generally ineffective due to inaccurate temperatures readings caused by accumulation of dust and dirt on temperature sensor surfaces. Air filters have been proposed to control dust and dirt accumulation, but these filters have been difficult to access for cleaning or replacement.
There exists, therefore, a significant need for improvements in and to water coolers of the type having a thermoelectric heat transfer module for chilling water within a cooler reservoir, particularly with respect to providing an improved system for regulating the module in a manner to prevent excessive ice bank build-up while reducing overall energy requirements. Moreover, there exists a need for further improvements with respect to facilitated access to an air filter associated with a heat sink cooling fan. The present invention fulfills these needs and provides further related advantages.